SK5332000A3 - Method of preparing a dairy spread - Google Patents

Abstract

Dairy spreads, especially fresh cheese, are sensitive for heat treatments. The heat treated products are often grainy, mealy and chalky. The invention relates to a method of producing a dairy spread wherein a cheese milk or cream or a combination thereof is acid coagulated in the presence of a suitable culture, wherein the culture comprises an exopolysaccharide producing lactic acid bacterium capable of reducing the graininess of the heat treated dairy spread.

Description

A method for producing a milk spread and a food product

Field of the invention

The invention relates to a process for the production of dairy spreads and to food production prepared by this process.

BACKGROUND OF THE INVENTION

For the purposes of the present invention, dairy spreads are those containing acid-based products. Milk spreads are generally made from a suitable mixture of concentrated milk protein and fat sources, which are acidified and further processed, optionally removed. Examples of dairy spreads are spreadable butter, yoghurt spreads, margarines that contain fermented dairy ingredients, fresh cheese, cheesecake, shapes and cream cheese.

Preferred products are fresh cheese and other spreadable products containing at least 5 wt. fresh cheese.

For the purposes of the present invention, the term spread means a plastic, paintable product that can be spread on bread at room temperature substantially without crumbling.

Milk spreads can be made, for example, as follows: milk or cream is adjusted to have the desired fat and protein content and fermented, e.g. through a starter culture, and optionally warm up. When the pH exceeds the isoelectric point of the rennet (approximately 4.6), the protein coagulates to form a spread. Optional steps of the procedure are whey removal and homogenization during or after coagulation.

The fat in the dairy spread may originate from milk or other source and may be added (or a portion thereof) after fermentation.

Optionally, additional components, e.g. butter, cream, herbs, spices, salt, binding and / or structuring agents. If the coagulation is caused by a combination of acid and heat effects, the pH of the coagulation may be substantially higher than 4.6.

-Fresh cheese differs from other cheeses in that the coagulation of milk proteins is caused by the action of the acid, which is produced e.g. by a starter culture, and optionally by heat, and not by an enzyme such as rennet, and in that the fresh cheese does not ripen and is ready for consumption after completion of the manufacturing operations. Rennet may be used to prepare fresh cheese, but in relatively small amounts, as an additive component of the acidifying components. In such an application rennet is considered to serve to improve the resulting properties of the product and to improve the efficiency of the coagulation process. However, the primary factor that causes coagulation is acid, optionally in combination with heat.

In the case of production of fresh cheese, whey is generally removed after coagulation, and a heating and / or homogenization step may be included after, during or before whey removal.

After manufacture, the dairy spread is usually filled hot or warm into molds or containers, allowing it to cool, and stored at low temperatures. After obtaining sufficient rigidity by cooling, if desired, a milk spread can be removed from the molds or containers.

A problem in the preparation of dairy spreads is the occurrence of less preferred structures. Milk spreads are, for example, often grainy, meaty and chalked. These less preferred structures are observed, especially when heating is used in the preparation process.

For the purposes of this invention, heating is defined as heating a dairy spread to a temperature greater than 58 ° C for more than 1 second.

In general, heating can be used, for example, to prolong the shelf life of the products by inactivating lactic acid-producing bacteria that would otherwise cause further acidification of the products during subsequent storage.

During this heating step, further significant aggregation of milk proteins can occur, resulting in various defects in the perception of the spread in the mouth: a feeling of granularity, sandiness, swelling, or chalkiness in the mouth. Homogenization may be applied to modify the structure, especially the mouthfeel, but very often the results are not satisfactory and the product remains grainy or meaty. Generally, the consumer does not accept a grainy, meaty or chalk feeling in the mouth.

Accordingly, there is a need to find ways to improve the feeling of milk spreads in the mouth, especially milk spreads that have been heated during preparation.

It has previously been proposed to add stabilizers such as locust beans, guar gum, gelatin, starch and the like to dairy spreads to improve their quality. However, in general, the consumer does not prefer to use such ingredients.

It is an object of the present invention to provide a selection of natural ingredients that can be added to a dairy spread composition to reduce sand or granularity even when heating is applied. Surprisingly, it has been found that it is advantageous to include specific exopolysaccharide-producing bacteria.

The general incorporation of bacteria in dairy products has been described in the literature.

For example, EP-A-111 020 describes the use of a specific combination of bacteria for the production of a dense sour milk product.

EP-A-639 332 describes a process for producing cheddar cheese with reduced fat content. A culture system comprising a fiber culture is used. Cheddar is a cheese product that cannot be coated. In the process of cheddar production, the raw milk is acidified with a starter culture for 30 minutes and then matured in the presence of rennet for 30 minutes.

EP-A-196 436 describes the use of a mixture of different Streptococcus cremoris bacteria for the manufacture of cottage cheese. The curd mixture is neither heated nor homogenized.

EP-A-331 564 describes the use of a polysaccharide from a specific Streptococcus thermophilus culture as a thickening agent, for example for the production of yoghurt.

The aim of US-A-4,243,684 is to reduce the softness of soft cheese such as Camembert, Brie, Romadur, Limburger and Muenster by using fiber cultures. In these products, coagulation is primarily effected by rennet. No heating is applied after coagulation. In the dairy spreads of the invention, coagulation is primarily carried out by acidification.

WO-A-94/12656 discloses specific Lactobacillus sake strains capable of producing exopolysaccharides in products such as margarines and dressings.

FR-A-2 154 371 relates to fresh cheese products, such as yoghurts, which are acidified to a certain pH and subsequently consumed. As stated

The products do not heat up after coagulation, they most likely contain live, active lactic acid-producing bacteria.

WO-A-92/02142 discloses novel donor bacteria which contain a plasmid DNA fragment which encodes a viscosity enhancer for a milk-containing product. Said bacteria may be used to produce buttermilk, sour cream and cheese. Those products are considered to contain live bacteria since they have not been heated after acidification.

EP-A-82581 relates to sour milk products, e.g. yoghurt, which contain specific lactic acid producing bacteria, which are interconnected by fibers of biopolymers. Said products are allowed to ferment and the resulting product is then ready for consumption.

Sebastiani, H (DMZ Lebensmittel Industrie und Milchwissenschaft, Vol. 115, No. 12, June 9, 1994, page 586) discloses the use of the Streptococcus thermophilus strain for the production of exopolysaccharides. Said strains are useful for fermentation of sour milk and soft cheese products.

Obert, G (Magyar Tejgazdasag Kiserleti Intezet, Pecs, Hungary. Tejipar. Vol. 33, No. 2, pp. 47-48, 1984) describes the preparation of turo cream using a heat-resistant and slime-resistant strain of Streptococcus thermophilus, and which allegedly improves the deformation properties. These products are packaged at 60 ° C without killing the slime producing bacteria.

In either case, the specific problem of the smoothness of products containing an acid casein network and which has been heated has not been discussed.

Surprisingly, it has now been found that specific exopolysaccharide-producing lactic bacteria can advantageously be used to produce heated dairy spreads, thereby obtaining non-granular or non-sand products.

Even more surprisingly, it has been found that dairy spreads, such as fresh cheese, produced by lactic acid bacteria producing exopolysaccharides can be heated without losing their homogeneity, non-granular or non-sandy appearance and texture.

-5-Summary of the invention

SUMMARY OF THE INVENTION The present invention provides a method for producing a dairy spread by coagulating raw milk or cream or a combination thereof with an acid in the presence of a suitable culture and subsequently heating, said culture comprising dairy bacteria producing exopolysaccharide capable of reducing the grain size of the dairy spread. .

Acid coagulation may optionally be followed by whey removal and / or homogenization in any order.

A further embodiment of the invention relates to a process for the production of fresh cheese, which comprises acidifying the milk in the presence of a suitable culture, followed by, in any order, separating the whey and heating, wherein the culture comprises lactic acid bacteria producing exopolysaccharide and capable reduce the grain size of fresh cheese.

A suitable culture for use in the product of the invention comprises exopolysaccharide (EPS) producing lactic acid bacteria which are capable of reducing the grain size of the milk spread. Although EPS producing bacteria can form part of the present starter cultures to provide a smooth structure, it is preferred that they form the least significant part of the starter culture. Other cultures may be added to the EPS bacteria, for example to increase the rate of acidification of the dairy spread, or to contribute to the resulting taste of the product.

For the purposes of the present invention, it has been found that not all EPS producing lactic bacteria are able to reduce the graininess of the heated dairy spread. However, it is the view of the Applicants that the person skilled in the art is able to determine without difficulty which EPS producing lactic acid bacteria are suitable based on the following guidance.

For example, the first, probably the most appropriate test (a) to determine the ability to reduce graininess is to produce a dairy spread, such as fresh cheese, by standard preparation using EPC-producing lactic acid bacteria and to compare the grain size of the product with the product made in the same way by acidification in the presence of non-producing lactic acid EPS. This test is preferably performed for dairy

-6 low fat spreads. Significantly reduced grain size, mouthfeel of dairy spread for which the lactic acid producing EPS was used, compared to products using non-lactic acid producing EPS, indicates the ability to reduce the grain size of the heated lactic spreads. This method is illustrated in the examples.

Preferably, this grain size reduction in Test (a) is determined by a trained consumer group. The grain size is then counted on a scale of 1 to 5, 1 being a smooth, non-grain sample and 5 being a very granular sample such as cheesecake or other friable products. Preferably, at least 8 out of 10 participants of the tasting event report a reduction in grain size of at least two units on a scale of 1 to 5 for suitable EPS producing cultures.

Other tests have been developed to determine which EPS producing lactic acid bacteria are suitable for reducing the granularity of the heated lactic spreads. A combination of two or more of these assays will show whether EPS producing lactic acid bacteria are suitable for reducing the graininess of heated dairy spreads.

A second suitable test (b) for determining the grain-reducing ability is to produce a milk spread, for example fresh cheese, and to determine the grain size of the product by determining the particle size distribution of the diluted spread dispersions, the grain size being reduced if the larger particle size is reduced. Preferably, the particle size distribution is such that less than 10 vol. %, more preferably less than 7 vol. % of the particles are larger than 18 µm. This method is illustrated in the examples.

The ability of EPS producing cultures to reduce the graininess of heated spreads can be further determined by screening EPS cultures in milk. A suitable test (c) for determining the grain-reducing ability is to determine the modulus of elasticity G 'and G' as a function of the temperature of milk samples fermented with various EPS producing lactic acid bacteria. Both G 'and G' are very sensitive protein aggregation probes in these samples.

A sudden change in G * and G 'upon slow heating of the sample indicates (heat-induced) aggregation of protein particles. In our experience, protein aggregated particles are formed during heating and are a major cause of milk spreads. Due to the difference of G * and G 'in relation to temperature it is thus possible

- infer the ability of EPS producing cultures to prevent protein aggregation during heating and to reduce the graininess of dairy spreads. More specifically, the relatively flat profile G * and G 'above the temperature, in the range of 40 ° C to 60 ° C, implies the ability to reduce the graininess of the heated dairy spreads.

The following equation for reduction in log G 'can be used to quantitatively change the theological parameters by G ‘and G':

Reduction factor = 100% * [log G '(40 ° C) - log G ‘(60 ° C)] / log G‘ (40 ° C) where G * is in Pa.

This reduction factor expresses the temperature dependence of log G ‘for a temperature in the range of 40 ° C to 60 ° C.

Preferably, the reduction factor as defined above is less than 35%, more preferably less than 30%. This method is also illustrated in the examples.

Another suitable test (d) is to determine the loss of water from milk samples acidified with various EPS producing lactic bacteria. Samples prepared with suitable EPS producing cultures are less heat sensitive. The heating in this assay may be, for example, heating at 80 ° C for 1 hour. For suitable cultures, the water loss after such heating, at a product pH of about 4, is less than 20 wt%, more preferably no water loss (less than 5 wt%) is detected from the milk sample after heating, at a product pH of about 4.

Another suitable test (e) is to determine whether the exopolysaccharide molecules are charged. We have found that the formation of uncharged exopolysaccharides indicates the ability of cultures producing uncharged EPS to reduce the graininess of heated dairy spreads. The method for determining the charge of EPS molecules is illustrated in the examples.

Another suitable test (f) is to determine whether EPS forms capsules around the bacteria that produce it. This assay can be performed, for example, using a confocal scanning laser microscope, using a conventional protein staining agent, such as rhodamine. If the bacteria are surrounded by a layer of EPS and essentially no proteins are present, it follows that the culture is suitable for reducing the graininess of the milk spreads. The EPS layer around the bacteria is also called

-8 capsule around bacteria. Accordingly, the fact that the bacteria are encapsulated by EPS indicates that these bacteria may be suitable to reduce the graininess of the milk spreads. Preferably, test (f) is applied to samples that have not been severely cut. This test is less suitable for cut products as the capsules can be destroyed by cutting.

Another suitable test to determine the ability to reduce graininess is to measure the hardness of the milk spread before and after the pasteurization step. Usually the hardness increases considerably after pasteurization. Hardness in the context of the present invention is defined as the maximum resistance measured during product penetration. Preferably, the variation in the hardness of the product produced by a suitable EPS-producing culture is relatively low compared to a product for which no EPS culture has been used.

A preferred embodiment of the invention relates to a method for producing a milk spread comprising coagulating raw milk or cream or a combination thereof with an acid in the presence of a suitable culture, wherein the culture comprises a lactic acid producing exopolysaccharide which produces EPS which is uncharged and forms a capsule around the bacteria .

Applicants have found that particularly suitable EPS producing cultures for use in the present invention are Lactobacillus delbrueckii supsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766.

However, in view of the above guidance, Applicants are sure that the skilled artisan will be able to identify other suitable cultures without difficulty.

For the purposes of the present invention, for ranges comprising the term "from (a) to (b)", these are defined as ranges from including (a) to including (b).

Preferably, the final dairy spread has a dry matter content of from 5 to 70 wt%, more preferably from 15 to 65 wt%.

The fat content of the milk spread is from 0 to 60% by weight, preferably from 0 to 40% by weight. fat.

The fat content of the milk spread may be up to 80% by weight, more preferably from 0 to 75% by weight. dry weight product. Exceptionally good products are obtained if from 10 to 75% by weight, in particular from 40 to 60% by weight. The dry dairy spread represents fat.

Particularly good product improvements are obtained with 0 to 40 wt. % by weight and a dry matter content of from 15 to 65 wt. in combination with a method comprising a homogenization step.

Milk fat is the preferred fat, but vegetable fat may also be used instead of all or part of the milk fat. Preferably, the product according to the invention comprises at least 30 wt. % milk fat based on total fat, more preferably at least 60 wt. with respect to total fat.

Although it is very advantageous to produce a smooth non-granular product using only suitable EPS producing lactic acid bacteria, other ingredients such as from 0.1 to 5% by weight may be included. % of the binding and / or structuring and / or stabilizing agent in an amount of from 0.1 to 3% by weight, in particular a range of from 0.3 to 1.5% by weight is preferred. Preferred binding or structuring or stabilizing agents are whey protein, which is preferably in the form of whey protein concentrate, acacia teat jelly, carboxymethylcellulose, gelatin and mixtures thereof.

Such binding and / or structuring and / or stabilizing agents may be advantageous to obtain a very well-stabilized form of a dairy product such as fresh cheese at elevated temperature to obtain a stable product that does not have negative properties such as oil deposition or liquid-gel separation. . However, preferably the total level of stabilizing or binding or structural components is less than 0.1 wt%, more preferably 0. Preferably, the above ingredients are added after acidification of the milk spread. If whey is separated, optional ingredients are added preferably after the whey has been separated.

According to one embodiment, the dairy spread is prepared by a process comprising the following steps:

(a) acidifying milk or cream, or combinations thereof, which include lactic acid bacteria producing exopolysaccharide and, optionally, other acidifying cultures for coagulation;

b) heating, optionally removing whey, and optionally introducing additional ingredients, in any order;

(c) filling the product in its final packaging.

A preferred method involves removing whey in step b) after heating.

The milk or cream or a combination thereof used in step a) may be conventional milk or cream standardized to a particular protein and / or fat content according to the desired end product and the process used. The milk may also be reconstituted milk powder. The milk or cream may contain other substances, e.g. buttermilk, skimmed milk, milk fat, vegetable fat, etc. The milk or cream may be pasteurized and / or heated to a high temperature and / or homogenized.

The milk or cream is acidified by a starter culture that contains exopolysaccharide producing lactic acid bacteria and optionally a small amount of rennet is included.

Coagulation is preferably due to the effect of acid and not the combined effect of acid and heating. Accordingly, the fermented milk in which coagulation has taken place, preferably has a pH of from 4.5 to 5.0, more preferably from 4.6 to 4.9.

Acidification and coagulation can be stopped by heating according to step (b), for example above 58 ° C for 5 minutes.

Optionally, whey is separated, preferably by ultrafiltration (UF) or centrifugation in a separator.

The heating according to step (b) may serve to obtain an increased density of the sour curdled milk and to pasteurize the product. It can be applied before or after whey removal. Heating to increase density can be combined with heating to terminate acidification.

The heating according to step (b) is preferably carried out at a temperature above 60 ° C, preferably 65 to 100 ° C, more preferably 70 to 80 ° C, most preferably 75 to 80 ° C.

Furthermore, it may be useful to homogenize the sour curdled milk, e.g. passage through a homogenizer. Homogenization can be applied as long as the product has an elevated temperature. Preferably, the homogenization is carried out in a homogenizer operating, e.g. at a pressure of at least 5 MPa (50 bar), preferably 7.5 to 50 MPa (75 to 500 bar), in particular 10 to 30 MPa (100 to 300 bar).

Optionally, according to another embodiment, in step (b), whey is removed after heating, followed by a further heating and homogenization step.

The composition of the milk or cream and subsequent processing may be selected such that the product obtained is suitable for packaging without the addition of additional ingredients immediately after the step

-11 (a) as described above, or with the addition of only some ingredients for taste, aroma and appearance, e.g. salts, flavorings, herbs, spices, etc.

Herbs and other materials that contain discrete particles to remain recognizable in the final product are preferably included in the final stages of the process, preferably just prior to extrusion. If materials containing such discrete particles are to be introduced, it is particularly desirable for hygienic reasons that the product be pasteurized after the introduction of such materials. If possible, the product surface may be coated with the desired materials, e.g. part or all of the surface of the product may be covered with a layer of herbs, pieces of hazelnut, etc.

Ingredients which may not be recognizable as such in the final product, e.g. salt or spices may be introduced at an earlier stage of the process, but preferably such introduction is carried out at a stage after optionally removing whey.

Similarly, if desired, other components, e.g. cream, butter, vegetable fat, structuring and / or binding and / or stabilizing agents, etc. added at several stages of the above process, but preferably after optionally removing whey.

The products of the invention may be mixed with other food products. Therefore, the invention also relates to dairy spreads containing acidified milk-based products prepared according to the invention. Any suitable products based on acidified milk may be used. The amount of acidified product is preferably greater than 5 wt.

A preferred product according to the present invention is fresh cheese which can be consumed as such. It is also possible to mix the fresh cheese product with, for example, butter, yoghurt, margarine, vegetable fat spread, cheesecake, mozzarella, cottage cheese, cream cheese, cream fraiche or thick cream obtained by collecting slowly heated milk. The product may be mixed homogeneously to obtain a mixed product or non-homogeneous, thereby combining the fresh cheese component and the other component in a packaged dairy spread. The mixed products preferably contain at least 5 wt%, more preferably at least 15 wt%, most preferably at least 50 wt%. fresh cheese according to the invention.

The most preferred product according to the invention contains more than 90 wt.

fresh cheese.

Preferably, the products of the invention have a long service life. Longevity is defined as the shelf life of an article having a closed shelf life of at least 3 weeks, preferably at least 6 weeks, in particular at least 8 weeks, wherein the article does not exhibit increased acidity or changes in taste or texture changes compared to the product just manufactured. Said long life can be obtained, for example, by heating after coagulation to a temperature that is sufficiently high and for a time that is long enough to kill substantially all of the bacteria so that acidification is not continued in the package. Applicants have found that heating to a very low temperature for a short period of time cannot kill bacteria; on the other hand, heating to a very high temperature for a long time can lead to products with an undesirable structure. Therefore, the heating is preferably carried out at a temperature above 60 ° C, more preferably from 65 to 100 ° C, most preferably 70 to 80 ° C. The heating preferably takes from a few seconds to 20 minutes, preferably from 10 seconds to 15 minutes, in particular from 1 to 5 minutes. The product of the invention is preferably substantially free of live lactic acid bacteria. The invention will be further illustrated by non-limiting embodiments thereof. Parts and percentages in the following description refer to weight unless otherwise indicated.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1 shows graphs of measurements in an oscillating cutter using a Carrimed CSL 500 rheometer. The x-axis shows the temperature in ° C and the y-axis shows the ratio G G / G v in the log scale.

In FIG. 2 shows the particle size distribution for two fresh G and H cheeses prepared according to the method of Example 4.

In FIG. 3A, 3B and 3C are images obtained with a BioRad MRC600 microscope using a confocal scanning laser microscope. Fig. 3A relates to Lactobacillus delbrueckii subsp. bulgaricus 291, FIG. 3B Lactobacillus helveticus NCDO 766 and FIG. Lactococcus lactis supsp. cremoris H414.

13 Examples of embodiments of the invention

General procedures

In the examples, the following standard method of preparing spreadable fresh cheese is used.

Pre-culture preparation

Sterile skim milk is inoculated with 0.5% culture, which was stored at -80 ° C as a fully grown skim milk culture, diluted with sterile 10% glycerol to a final glycerol volume of 6%. Inoculated sterile skim milk (called pre-culture) is fermented for 16 hours at 35 ° C for mesophilic culture and at 37 ° C for thermophilic culture.

Preparation of fresh cheese

The raw milk is pasteurized at 72 ° C for 30 seconds. The milk is then standardized to 2.5 wt. fat. 1 wt. % mesophilic or 2.5 wt. % of thermophilic milk pre-culture is added together with 0.001 wt. rennet. In addition, 1 wt. a further acidification culture to increase the rate of acidification of the dairy spread; f. e. Streptococcus thermophilus strain. The milk is acidified to pH 4.8 at 23 ° C for about 16 hours for mesophilic culture and at 43 ° C for about 3 hours for thermophilic culture. The product is then heated at 60 ° C for 5 minutes, followed by ultrafiltration to remove a portion of the whey until a dry substance content of 28% is reached. The product is then mixed with 0.7 wt. of salt and reheated to 75 ° C for 10 minutes. The product is homogenized in a homogenizer operating at 20 MPa (200 bar) and filled into tubes. The final product contains approximately 10 wt. % fat, 13 wt. proteins and about 28 wt. dry matter.

The following examples illustrate the methods described above. If test (a) is used to determine the ability of EPS producing cultures to reduce the graininess of dairy spreads, a second test is not required. Test (a) was performed in Example I and Example IV. If any of the tests (b to f) is used, a combination is required

-14 two or more tests to get a reliable result. Therefore, the results of the two tests selected from Examples II, III, V and VI should be combined prior to concluding on the ability of EPS producing cultures to reduce the graininess of dairy spreads.

Example 1

Two fresh cheeses were prepared according to general procedures

Fresh cheese A was prepared using 50 parts (1% by weight) of Lactobacillus delbrueckii supsp. bulgaricus 291 and 50 parts (1 wt%) of Streptococcus thermophilus strain as thermophilic pre-culture. Acidification was carried out at 43 ° C until a pH of 4.8 was reached. Fresh B cheese was prepared using 2.5 wt. Lactococcus lactis supsp. cremoris H414. Acidification was carried out at 23 ° C until a pH of 4.8 was reached.

The products were tested to determine their grain size according to method (a) described above. Product A (according to the invention) had a significantly reduced grain size compared to product B (comparative product).

Example 2

Three milk samples were prepared as follows:

Sterile skim milk was fermented with 1 wt. culture.

Sample C was fermented at 37 ° C with Lactobacillus delbrueckii subsp.

bulgaricus 291 to pH 3.8.

Sample D was fermented at 37 ° C with Lactobacillus helveticus NCDO 766 to pH 3.7.

Sample E was fermented at 20 ° C with Lactococcus lactis supsp. cremoris

H414 to pH 4.2.

Measurements were performed in an oscillating cutter (G *. G) using Carrimed

CSL 500 rheometer (symmetrical cone plates), increasing the temperature from 10

-15 ° C to 60 ° C at a rate of 2.5 ° C / min. The results are shown in Figure 1. The x-axis shows the temperature in ° C and the y-axis shows the proportion of G '/ G' on the log scale.

For sample C (according to the invention), the graph of G ‘in Pa over temperature was more or less a flat line with G‘ (at 10 ° C) about 200 Pa and with G ‘at 60 ° C of 25.3 Pa. The graph of G "in Pa versus temperature was also more or less a straight line with G" at 10 ° C of about 50 Pa and G "at 60 ° C of about 10 Pa. These straight G * and G 'profiles indicate the stability of the sample when heated.

G ‘(40 ° C) = 61.8 Pa

G ‘(60 ° C) = 25.3 Pa

Reduction factor = 22%.

A reduction factor of less than 35% indicates that the cultures are suitable for reducing the graininess of dairy spreads.

For sample D (according to the invention), the graph of G 'in Pa versus temperature was more or less a flat line with G * at 10 ° C of about 50 Pa and with G' at 60 ° C of about 10 Pa. The graph of G "in Pa versus temperature was also more or less a straight line with G" at 10 ° C of about 12 Pa and G "at 60 ° C of about 3 Pa. Again, these straight G * and G 'profiles indicate the stability of the sample when heated.

G ‘(40 ° C) = 21.2 Pa

G ‘(60 ° C) = 9.4 Pa

Reduction factor = 27%.

A reduction factor of less than 35% indicates that the cultures are suitable for reducing the graininess of dairy spreads.

For sample E (comparison), the graph of G 'shows a significant descending band in the region between 40 ° C and 50 ° C, with G' at 10 ° C approximately 50 Pa, at 40 ° C approximately 25 Pa, at 50 ° C about 3.5 Pa and with G 'at 60 ° C about 2 Pa. G at 10 ° C was about 20 Pa, at 40 ° C was about 9 Pa, at 50 ° C was about 2 Pa, and G "at 60 ° C was about 2 Pa.

G ‘(40 ° C) = 23.8 Pa

G ‘(60 ° C) = 2.9 Pa

Reduction factor = 66%.

A reduction factor greater than 35% indicates that these cultures are not suitable for reducing the graininess of dairy spreads.

According to test (c), suitable exopolysaccharide-producing starter cultures can be selected for use in preparing the milk spread of the invention by measuring the G * and G 'profile as above. The reduction factor defined herein is preferably less than 30%.

This example shows that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 may be suitable cultures for reducing the grain size of dairy spreads.

Example 3

Sterile skim milk was fermented with 1 wt. pre-cultures as described in Example 2 for samples C to E. Sample F was obtained by inoculating sterile skimmed milk to which 0.35% yeast extract, 0.35% peptone, 1% glucose and 50 mg / l MnSO was added. ₄ , 0.5% Lactobacilus sake 0-1 culture, which was stored at -80 ° C as a fully grown culture in the above milk base medium, diluted with sterile 10% glycerol to a final glycerol concentration of 6%. The pre-culture thus obtained was grown for 16 hours at 20 ° C and was then used to prepare Sample F by inoculating the supplemented milk base medium with 1% pre-culture and fermenting it to pH 4.3. Samples C to F were then heated to 80 ° C for 1 hour and water loss was then determined. The results are shown in Table 1.

Table 1

Water loss after heating to 80 ° C for 1 hour

sample

C

D

E

F

Water loss (%) at pH 4 10 0

By test (d), suitable exopolysaccharide-producing starter cultures can be selected for use in the preparation of the dairy spread of the invention by measuring the loss of water on heating as above. Less than 20 wt. the loss of water in the product after heating at a pH of about 4 indicates suitable EPS producing lactic bacteria. More preferably, there is no water loss. As a result, samples E and F do not provide suitable cultures to reduce the graininess of dairy spreads.

This example shows that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 may be suitable cultures for reducing the grain size of dairy spreads.

Combining this result with the test result described in Example 2, it can be concluded that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 may be suitable cultures for reducing the grain size of dairy spreads.

Example 4

The raw milk is pasteurized at 90 ° C for 15 minutes. In addition, two fresh cheeses were prepared in accordance with the general procedures. Fresh G cheese (according to the invention) was prepared using a thermophilic culture of Lactobacillus delbrueckii subsp. bulgaricus 291 and Streptococcus thermophilus strain in a one to one ratio. Fresh H cheese (comparison) was prepared using mesophilic Flora Danica culture (ex. Chr. Hansen's).

The products were tasted to determine their grain size according to Test (a) described in the description. Product G had a significantly reduced grain size compared to product H.

Example 5

The rotational particle size was then measured: approximately 0.5 g of fresh cheese was dispersed in approximately 25 ml of water. The suspension was stirred for 20 minutes. Helos / SUCELL was brought to an optical concentration of between 15 and 20%. The measurement time was 10 s and focal distance 200 mm, time resolution 1000 ms.

Two fresh G and H cheeses were prepared according to the method of Example 4. The particle size volume distribution is shown in Figure 2.

According to Test (b), as described in the application, these examples demonstrate that the grain size of fresh cheese is reduced when the larger particle size is reduced. Preferably, the bulk particle size distribution is such that it is less than 7% by volume. particles having a size greater than 18 µm. Figure 2 shows that a sample of fresh cheese (G) acidified with Lactobacillus delbrueckii subsp. bulgaricus 291 contains 5% of particles larger than 18 µm. Accordingly, the culture may be suitable for reducing the grain size of fresh cheese. When this result is combined with the test results from either Example 2 or Example 3, it can be concluded that said culture is able to reduce the grain size in fresh cheese. Comparative Sample H contains approximately 9% of particles larger than 18 µm, indicating that this is not a suitable culture to reduce graininess in dairy spreads.

Example 6

Fermented milk samples according to Examples 2/3 were prepared as follows:

Sterile skim milk was fermented with 1 wt. culture.

Sample C was fermented at 37 ° C with Lactobacillus delbrueckii subsp. bulgaricus 291 to pH 3.8.

Sample D was fermented at 37 ° C with Lactobacillus helveticus NCDO 766 to pH 3.7.

Sample E was fermented at 20 ° C with Lactococcus lactis supsp. cremoris H414 to pH 4.2.

Sample F was fermented with Lactobacillus sake 0-1 at 20 ° C, to pH 4.3.

Example 6A

Isolation and purification of EPS from the fermentation broth was performed as follows. The protein was removed from the culture medium by addition of trichloroacetic acid until a concentration of 4% was reached. After gentle mixing, the culture was allowed to stand at room temperature for 30 minutes. The culture was centrifuged for 30 minutes

-19 minutes at 13,000 g and a clear supernatant was collected. The EPS formed precipitated with 1.5 times the volume of cold ethanol. The precipitate was collected, redissolved and dialyzed against demineralized water for 2 days at 10 ° C. The water was changed twice a day. The material was then freeze-dried and stored under dry conditions.

Two different methods are used to determine whether the EPS is charged as described in Test (e).

(1) A solution of 0.5 wt. of a positively charged polysaccharide, chitosan in water between pH 4 and 5. It is important that the chitosan dissolves completely to make the resulting solution clear. An equal amount of 0.5 wt.% Was added to this clear solution. EPS solution. Mixing of the solutions was carried out at room temperature. If precipitates are formed, it can be concluded that the added EPS is charged. If the solution remains clear, it is an uncharged EPS, which further suggests that the culture from which it was isolated may be a suitable culture to reduce graininess in dairy spreads.

(2) Another way to determine if EPS is charged is to perform electrophoresis in a Zetasizer 3 apparatus from Malvern. In this way, the electrophoretic mobility of the isolated EPS is measured. An aqueous solution of isolated, concentrated EPS (0.1 wt%) is loaded into an electrophoretic cell. If the measured electrophoretic mobility is substantially zero, the EPS is uncharged.

The above two experiments were performed for EPS isolated from samples C, D, F. The EPS results from samples C and D resulted in a clear solution in the first experiment described above (1) and showed no electric field movement in the second experiment described above (2) . Based on these results, it can be concluded that EPS produced by Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO is uncharged. EPS isolated from sample F resulted in the formation of a precipitate in the first experiment (1). Experiment (2) showed that EPS from sample F moves towards the positive electrode. From this it can be concluded that EPS isolated from Lactobacillus sake 0-1 is negatively charged.

Referring to test (s) in the description, the fact that a culture produces uncharged polysaccharides implies the ability of cultures producing uncharged EPS to reduce the graininess of dairy spreads.

Example 6B

To prepare samples for scanning confocal laser microscopy (CSLM) according to test (f) in the description, dairy samples C to E were fermented to pH 5.5 and heated at 60 ° C for 5 minutes to stop acidification. Subsequently, the heated samples were plated on CSLM microscope plates. Protein and bacteria were stained with rhodamine B. Rhodamine staining was performed according to general textbook procedures as described, for example, in Nizo Nieuws 1995, no. 9, p. 13-15, M. E. Maria and P. Zoon. It is important that the pH of the samples is higher than the pH of protein aggregation, preferably higher than 5.5. Samples were studied by CSLM. EPS is not directly visible as it is not colored, but can be seen as a dark cover. The microscope used was a BioRad MRC600 confocal scanning laser microscope.

The results are shown in Figures 3A-3C. The image width in all photos is 65 pm.

Figure 3A relates to Lactobacillus delbrueckii subsp. bulgaricus 291, Figure 3B relates to Lactobacillus helveticus NCDO 766 and Figure 3C to Lactococcus lactis supsp. cremoris H414.

In Figures 3A and 3B, EPS can be seen as a dark wrap around bacteria. A protein stained with rhodamine B is visible as colored spots. In both Figures 3A and 3B, it is clearly seen that EPS forms a layer around the bacteria. There is essentially no protein present in this layer. In Figure 3C, there are no uncolored shells around the bacteria, and EPS is dispersed throughout the area outside the bacteria. Capsules cannot be identified.

Based on the above results, it can be concluded that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 form a capsule-like EPS which indicates that the culture is suitable for reducing graininess in dairy spreads. In contrast, Lactococcus lactis supsp. cremoris H414

-21 produces loose EPS, indicating that this is not a suitable culture for the products of the invention.

When the results of tests (e) and (f) are combined, i. of Examples 6A and 6B, suggesting that Lactobacillus delbrueckii subsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 are suitable cultures for reducing graininess in dairy spreads.

Claims (14)

PATENT CLAIMS A method for producing a milk spread, characterized in that the raw milk or cream or a combination thereof is coagulated by acid in the presence of a suitable culture and subsequently heated to a temperature higher than 58 ° C for more than 1 second, said culture comprising lactic bacteria producing exopolysaccharide - EPS which are capable of reducing the particle size distribution of a lactic acid, where the lactic acid bacteria producing exopolysaccharide meet the conditions of a combination of two or more of the following tests, provided that, if test (a) is used, no further test is necessary: (a) producing a lactic spread by a standard method of preparation using a lactic acid producing EPS and comparing the grain size of the product with a product produced in the same way but acidified in the presence of a lactic acid producing non-EPS lactic acid; the ability to reduce graininess in dairy spreads; (b) producing a dairy spread and determining the degree of granularity of the product by determining the particle size of the diluted dairy spread dispersions, wherein the volume particle size distribution, which comprises less than 10 vol. %, more preferably less than 7 vol. % of particles larger than 18 µm indicates an ability to reduce the graininess of the milk spreads; c) determining the G * module and the G 'module as a function of temperature for dairy samples prepared with various EPS producing lactic acid bacteria, wherein the relatively flat profile of G * and G above the temperature range of 40 to 60 ° C indicates the ability to reduce graininess of dairy spreads; d) determining the loss of water during heating of milk samples fermented with various EPS producing lactic bacteria at 80 ° C for one hour, wherein the water loss is less than 20% by weight; indicates the ability to reduce the graininess of milk spreads; e) determining whether the produced exopolysaccharide molecules are charged, wherein the production of uncharged EPS indicates the ability to reduce the graininess of the milk spreads; -23f) determining by confocal scanning laser microscopy whether the produced EPS forms a capsule around the bacteria producing it, wherein the production of the encapsulated EPS indicates the ability to reduce the graininess of the milk spreads. Method according to claim 1, characterized in that coagulation is followed by whey removal. Method according to claim 1 or 2, characterized in that the milk spread is homogenized after acidification. The method according to any one of claims 1 to 3, characterized in that the reduction factor as defined herein when it is less than 35%, preferably less than 30% in test (c) indicates that the cultures are suitable for reducing Milk spreads. The method of any one of claims 1 to 4, wherein the EPS produced by the lactic acid bacteria is substantially uncharged (test e) and forms capsules around the bacteria (test f). Method according to any one of claims 1 to 5, characterized in that the exopolysaccharide producing lactic acid bacteria meets the criteria of all processes (a) to (f). The method of any one of claims 1 to 6, wherein the exopolysaccharide-producing culture is selected from Lactobacillus delbrueckii supsp. bulgaricus 291 and Lactobacillus helveticus NCDO 766 and mixtures thereof. Method according to any one of claims 1 to 8, characterized in that the raw milk or cream or mixture thereof is heated to 80 to 100 ° C, 1 to 60 minutes, preferably to 85 to 95 ° C, 5 to 20 minutes before acid coagulation. -249. Method according to any one of claims 1 to 8, characterized in that the milk spread has a dry matter content of from 5 to 70% by weight, preferably from 15 to 65% by weight. Method according to any one of claims 1 to 9, characterized in that the fat content of the milk spread is from 0 to 40% by weight. fat and dry matter content is 15 to 65 wt. Method according to any one of claims 1 to 10, characterized in that the spread comprises from 0.1 to 5 wt. a binding and / or structuring and / or stabilizing agent selected from the group consisting of whey protein, acacia teat jelly, carboxymethylcellulose, gelatin and mixtures thereof. Process according to any one of claims 1 to 11, characterized in that the acidification is terminated by heating. 13. A food product comprising at least 5 wt. a milk spread which has been prepared according to any one of claims 1 to 12. 14. A food product comprising at least 5 wt. fresh cheese prepared according to any one of claims 1 to 12. Food product according to claim 14, characterized in that it contains 90% by weight of a food product. fresh cheese.